The country descended into violence in 2007 after the opposition, led by Odinga, claimed the election results were rigged in favour of the then incumbent Mwai Kibaki.

More than 1,000 people were killed in post-election violence and some 600,000 were displaced.

The chaos stopped after Kibaki and Odinga agreed to form a power-sharing government.

"Any attempt to try to cheat Kenyans of their victory will not be tolerated this time around," Odinga said.

Kenyatta, while addressing a campaign rally last week, denied attempts to rig the elections and said the allegations by opposition leaders were a ploy to form a coalition government.

"They [opposition] wasted their time on press conferences and fighting the Independent Electoral and Boundaries Commission (IEBC) in courts and now they have realised that they are headed for a defeat," Kenyatta told the crowd.

"That is why they are bringing up these baseless rigging claims," he said.

Msando's murder

The rigging claims come a week after the disappearance and murder of a senior electoral official.

The opposition, National Super Alliance (NASA), said the death of Chris Msando is linked to his role in the electoral body.

Msando who was the head of the election body's information, communications and technology.